Answer
"Deserve" refers to the accumulated balance of pious activities (puṇya) and sinful activities (pāpa) that one has acquired through previous actions.
One may compare it to a bank account.
Just as money is the currency with which we purchase material comforts, puṇya is the subtle currency through which material desires are fulfilled.
If a person desires a particular material enjoyment, he must possess sufficient puṇya for that desire to be fulfilled.
This is how the Lord deals with ordinary fruitive workers (karmīs). He is perfectly fair and impartial toward all living beings.
When a karmī desires something, the Lord does not simply grant the desire immediately. Rather, He provides guidance through the Vedic system, showing the person how to perform pious activities that will generate the necessary puṇya to fulfill those desires.
Material success is therefore not based solely on intelligence or effort. One must also possess the necessary stock of puṇya.
Without that accumulated piety, a person may desire something intensely yet still be unable to obtain it.
The situation is entirely different for a devotee.
A devotee's desire is not independent; it is aligned with the desire of Guru and Kṛṣṇa.
When a devotee sincerely desires to please Guru and Kṛṣṇa, the fulfillment of that desire does not depend upon his accumulated puṇya.
The Lord's mercy transcends ordinary karmic calculations.
Thus, even:
the lame can cross mountains,
and the dumb can become eloquent,
when acting in devotional service.
This is the unique position of a devotee.
Therefore, sincere devotees do not think that success in devotional service depends upon their own accumulated credit or qualification.
Instead, they understand that whatever they already possess has been given by the Lord, and whatever they lack will also be supplied by Him if it is required for His service.
Their confidence rests not in their own karmic balance but in the mercy of Guru and Kṛṣṇa.
